VP MD2020 tachometer repair

Instructions for making a technical contribution are on the parent page “Technical & Maintenance”.

By Barrie & Terry 19th January 2013

The type of Volvo Penta tachometer fitted with the MD 2020 engine is notorious for problems with the LCD engine hours run display.

During 2012 our LCD display kept fading, disappearing and then reappearing, all the while still accurately recording the engine hours run!

Eventually in early 2013 it died completely.

We tried warming it (as recommended on some forums), cleaning all the wiring connections etc with no success.

There were four options at this point:

  1. Do without an hours run meter.
  2. Replace the complete tachometer e.g. Keyparts sell one here http://www.keypart.com/volvo-penta/diesel-engine/md2020b/19941998     
  3. Fit a remote hours run meter e.g. from the Curtis Instruments range http://curtisinstruments.com/?fuseaction=Products.home#/vertical/72
  4. Replace the LCD in the tachometer.

We opted for number 4, partly to retain the ‘original’ look and partly because it was a relatively cheap solution (£21 including vat and delivery).

Fortunately we found a superb pictorial guide by Richard Davis on how to do this.

Volvo Penta tachometer LCD repair.pdf

There is also a Utube video showing the basic dis-assembly of the tachometer (see Note 2 below) https://www.youtube.com/watch?v=PFkSwD5-mfw

Notes for anyone considering this:

  • The Curtis LCD part number given in Richard’s guide seems to be no longer available but RS Components sell one that is suitable part number 185-6107
  • The depth of the replacement LCD is more than the original one which is why the aperture in the clear plastic faceplate has to be created, see picture 9 of Richard’s guide. The new LCD must be able to sit completely in the aperture and rest against the inside face of the black metal dial plate; otherwise the pins etc on the back may touch the PCB.
  • Before cutting the aperture, ensure that the display of the new LCD will line up squarely with the cut-out in the black metal dial plate!
  • To cut the aperture we used a Dremel (actually the Lidl’s version!) with a tiny cutting disc, and a selection of small fine files. The only other ‘special tool’ required is a small soldering iron.
  • The RS-supplied LCD is virtually identical to that in Richard’s picture 8. As shown in picture 11 (where the LCD is now upside down) the ‘P’ pin at top left and the ‘I’ pin at bottom right need to be wired together and the ‘P’  and ‘N’ (top right) pins wired to the positive and negative inputs of the PCB. Instructions that came with our new LCD are here: Tacho LCD instructions..
  • The + and – inputs are indicated on the back of the plastic plate with bayonets (into which the wiring loom plug fits) as shown in picture 12. When soldering the wires from the new LCD to the sockets for the bayonets, ensure that no solder goes inside, otherwise the bayonets may not insert properly.
  • Before replacing the needle, ensure that its spindle is turned fully anti-clockwise.
  • It may sound involved but actually we found this to be a straightforward job, albeit everything was on a small scale and rather fiddly for someone with chunky fingers. Most time was spent cutting the aperture in the clear plastic faceplate, taking care not to crack it.
  • On completion we then attached ours to a 12v transformer at home until it reached the actual engine hours.
  • NOTE 1: Poor connections on the Volvo PCB may be the cause of the problem and it may be possible to fix it by re-soldering them (instead of replacing the LCD as above) if you have a keen eye, steady hands and a fine-tip soldering iron. See comments from Victor Elliot and John A below.
  • NOTE 2 (added March 2016): An exact replacement for the original Volvo LCD complete with attached ribbon can now be bought for about £50 including postage from http://www.boatstuff.se/display-timraknare.html. Rickard, the proprietor of Boatstuff.se has also made this useful video to show how the instrument is dis-assembled: https://www.youtube.com/watch?v=PFkSwD5-mfw.  Although it is less work to fit, this original LCD will not correct a problem in the PCB joints, whereas the £15 one from RS should, as it has its own PCB on board the LCD.         

If you have found this page useful or can suggest improvement please leave your feedback below.     

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22 responses

  1. Hi Mark
    In the owners manual for the MD2020B Volvo Engine, the wiring diagram does show a brown cable leading from the alternator (generator in the manual)to the back of the standard instrument panel without a key switch but it seems to connect to warning light, charging. The diagram also shows a grey/black 1.5mm cable leading from the alternator to the s+ terminal on the Rev.counter. If you can confirm which of the three optional instrument panels you have, without key, with key or De luxe, I could Email you a copy of the relevant diagrams. Terry

  2. Can somebody tell me if the rev counter / hours meter is fed from the back of the alternator? I have a brown wire with a spade connector hanging in mid air behind the alternator. There is a spade terminal on the back of the alternator with nothing on it! Its a 2003 Volvo Penta MD 2020 installed in a Bavaria cruiser…..

  3. Yachtboatparts.com in Southampton UK sell original LCD screens that just plug into the volvo tacho and show the original hours.
    Takes about 10 minutes to replace.

  4. Adam,
    On ours there is only the 4way connector with wires as follows – blue+red, grey, black, black+grey.
    Regards
    Barrie

  5. Sorry if this is a dumb question.

    When refitting the tacho, as well as the 4way connector, should there be a red positive feed from the on/off switch to the single connector to the right of the 4 way?

    Thanks so much for an informative article.

    Adam

  6. I purchased a replacement LCD display from Boatstuff.se and it worked just fine! It took about 10 minutes to make the swap. Probably the most time consuming part was ensuring the needle was calibrated to 0 RPM at start up. I had to plug in the tachometer without the needle, turn on and then turn off the Acc, and lastly carefully reinstalled the needle at zero.

  7. Hello Mark,

    The instructions including the wiring diagram have now been added to the site here: Tacho LCD instructions

    This should help you.

    Best wishes.

    Barrie

  8. Hello Barrie and Terry,

    I have a similar tachometer and have replaced the LCD last year, however did not have the time to upgrade the number of hours as I had to install it in the boat immediately after

    Now this year I want to do this but wonder which of the 4 pins in the back are the + and – that I need to connect my battery to.

    Any help is much appreciated.

    Best regards,
    Mark Brussel

  9. Thanks for your feedback Robert, which may be of interest to others.

    Isn’t it satisfying when a dead display returns to life!

    In your case, it appears that the LCD itself was the problem rather than the PCB to which it attaches, as some others have reported.

    In our case, we didn’t know whether it was the LCD or the PCB and at the time a replacement original LCD wasn’t available.

    Using the Curtis unit available from RS Electrical is a much cheaper and more certain solution; as you say involving more time, but not at all difficult.

    By the way, we have no connection/financial arrangement with RS or any other company to which we provide links from this website!

    Best wishes,

    Barrie

  10. Many thanks for adding the link to http://www.boatstuff.se from whom I ordered the new LCD. Disadvantage – not as cheap as the Curtis Instruments display vastly outweighted by the advantages – straight swap, no special tools required, quicker to do, shows engine hours already accumulated Their video (link given above) was is also very helpful. To reduce possibility of corrosion I sprayed the socket on the circuit board with contact cleaner and put some white grease (vaseline would also do) on the ribbon contacts of the new LCD. I did the same for the four pins + – S+ and S- where they make contact with the cirucit board. Brilliant.

  11. Wow, I can’t believe how easy this was to do and also how much $$ I saved. Thank you very much

  12. Thanks a lot for a perfect guide to replace the hourmeter with a new one from RS-online. I did the swap without a problem. Easy to do for most people and hardly at no cost. One thing I should like to add though is that you should cut the hole in the plastic housing for the new hourmeter far bigger than the new hourmeter and instead glue the meter on the back of the black becel… And when guing the meter on the becel use a non-corrosive silicone glue (Dow Corning 744 is perfect) and add glue ONLY on the long sides of the hourmeter. In this way you will also have light in your hourmeter as the RS-online meter allows backlight to enter the hourmeter from the end of the hourmeter. Just to upgrade the swap 🙂 Glad we can help eachother.

  13. Following failure of my LCD hours meter, I replaced the Volvo Penta tacho with a new item which has started to record engine hours from 0. Does anyone know how to download the hours recorded on the old item?

  14. Tony,
    Sorry, we can’t help you with this one but maybe someone else who reads your post may be able to suggest what’s wrong.
    We had no problem of this nature – but then we replaced our hour meter (which has its own pcb) rather than try to clean or re-solder the existing pcb.
    Barrie

  15. I also had an hour meter problem with Volvo Penta VP 873 992 tacho and followed the cleaning proceedure mentioned.I replaced the tacho and now the rev counter is permanently at maximum and the hour meter is still faulty. Incidently I replaced the needle at zero after cleaning.Do you think the motor is now faulty as well,or do you have to reset something on the pcb.

  16. HI John, seen your post re non functioning LCD hours counter on a VDO/volvo penta rev counter. I have the same problem, i have cleaned the contacts on the ribbon, warmed it with a hair dryer,not sure where to go next? Any ideas gratefully received!
    Regards,Ian Rayner.

  17. Victor,
    Many thanks for your information.
    A reference to your comments is now included above.
    Regards

  18. I have repaired the hour meter in my tachometer fitted to my Sealine S23. No replacement parts were required as the fault was traced to dry joints on the tachometer circuit board. My tachometer had a hour display that would fade and sometimes dropout altogether. A fresh battery improved it for a short while but eventually failed. I purchased a new hour display as detailed above but found it was not required when I found the dry joints.
    The fault was found where the ribbon connector terminals pass through the circuit board. There are six connections which should be de-soldered and then very carefully re-soldered. You will need a fine soldering iron but once re- soldered my hour meter came back to life together with the correct hour reading. Cost would have been nil if I hadn’t read the earlier repair paragraph. Well worth the time spent as a replacement tachometer is mega bucks.

  19. Robert,

    In our case we started monitoring the engine run hours when we noticed the display fading and reappearing so we knew the total within an hour or so when the LCD finally went blank.
    After installing the new LCD we then attached the tacho to a 12v supply (a mains transformer at home) to clock up the required total hours, and then we reinstalled the tacho on the boat.

    See also the comment just made by John A about how he traced the same fault and repaired his VP tacho, WITHOUT replacing the LCD – and retaining the engine hours run data.

  20. Thanks John.

    This is somewhat beyond our capabilities but it may be useful to others.
    Our replaced LCD also continues to work well.
    ‘Dawntreader’ rings a bell – assuming it’s your boat name have we seen you today in Brixham or maybe Dartmouth?

  21. How do you “download” the actual engine hours off the old display if it has gone “transparent”?

  22. I had exactly the same problem on my motor boat. I have two Volvo Penta tacho’s with LCD engine hour meters (actually VDO). Being an electronic engineer I decided to delve a bit more deeply to try and identify the actual fault with these displays. I dismantled the meter and used an oscilloscope with a very high power magnifier I traced the fault to the connector between the motherboard and LCD display driver IC. I repaired both meters by cleaning and relaying the connector track with silver and epoxy. Not for the faint hearted as it requires a steady hand and eye as the connector tracks are only about 0.5mm width with a similar spacing. The repaired meters have been on the boat for three weeks now and are still working. One significant advantage of this approach is that the engine hour data held in memory is recovered and displayed.

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